


Survival of the Fittest

by ReineVix



Category: Undertale (Video Game)
Genre: (Undertale) Multiverse, Apathetic Oc!Papyrus (Undertale), Bloodthirsty Oc!Sans, Brutal Murder, Cannibalism, Dark Past, Dusttale Sans (Undertale), Horrortale Papyrus (Undertale), Horrortale Sans (Undertale), Killer Sans (Undertale) - Freeform, Language Barrier, M/M, Mobtale Papyrus (Undertale) - freeform, Mobtale Sans (Undertale) - freeform, Multiverse, Oc!Sans & Oc!Papyrus come from a Messed up Au, Original Character Papyrus, Original Character Sans, Original Male Character(s) - Freeform, Other Additional Tags to Be Added, Polygamy?, Reader Is A Skeleton, Ruthless Oc!Sans, Skeleton Reader, Somewhat BeastTale/PredatorTale, Souls, Tags Are Hard, Tags May Change, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Papyrus (Undertale), Underswap Sans (Undertale), harem?, monster reader, only time will tell, skeleton!reader, soul eating
Language: English
Status: In-Progress
Published: 2020-10-12
Updated: 2020-11-29
Packaged: 2021-03-08 02:28:49
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, No Archive Warnings Apply
Chapters: 5
Words: 7,925
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26964460
Author URL: https://archiveofourown.org/users/ReineVix/pseuds/ReineVix
Summary: |   Sans was the Apex Predator in a world of Demons, but he would rather dust himself then let his brother get close to any of these strange Monsters surrounding them. |Sans knew that mercy wasn't an option in this world, and he never felt any remorse for the killing or cannibalism he did in order to survive. Hell, he took pleasure in hunting down anyone who dared stand in his way. He was the Alpha of his race and the most feared and powerful Demon the humans had ever known, besides his cute little brother of course.Sans had been alive when the Humans came to their Realm, thousands upon thousands of defenceless, exhausted prey in a Realm of Ravenous Monsters. The feast that had took place shortly after was phenomenal and remembered as "The first Hunt".All Demons knew that Humans were prey, as long as you never gave them an opportunity to fight back. Which was why Sans was reasonably enraged and shocked when a human with glowing red eyes shoved him and his brother into a portal. When he wakes up to 13 odd looking demon's all looking vaguely like him and his brother speaking in some strange language, he's noticeably pissed off and confused.
Comments: 23
Kudos: 109





	1. Chapter 1

**Author's Note:**

  * Inspired by [Vindictive Care](https://archiveofourown.org/works/23845420) by [vindictiveskeletons](https://archiveofourown.org/users/vindictiveskeletons/pseuds/vindictiveskeletons). 



**The scent of iron seeped into the air, and the sound of frantic footsteps echoed through the forest as a young man came into view. Sobs leaving his mouth as he clutched his bleeding arm, hand covering a bloody wound. The man scrambled for footing as the forest got thicker and thicker, the pitch black darkness doing nothing to help as sharp brambles dug into his already aching legs painfully. The man sobbed, shrieking for help as he went deeper and deeper into the forest. A Ominous laugh rang through the tree's, and the mans face went pale with fear. He screamed as pain shot through his body as sharp bones pierced his body from behind. The man crashed to the floor, blood gushing onto the ground as he screamed out in agony. A deep laugh sounded again before the man felt his head suddenly be grabbed by tightly, pain blossoming as something sharp dug into his skull. "** ** _Better Luck next time."_** **was the last thing he heard** **before his head was brutally bashed into the forest floor.**

I grinned down at the bloodied corpse beneath me, feeling the rush of Adrenaline that made my soul pound. Another successful hunt. I released my hold on the humans skull, clawed phalanges coming up stained with blood. I chuckled faintly, I must have dug my claws into his head when I pinned him down. I flicked my hand and the sharp bones that had kept the man pierced to the ground evaporated immediately. The smell of blood coated the air and I breathed in deeply, running a forked tongue made of magic over my sharp teeth. I was so _hungry.._ I huffed, bending down even further then I already was and quickly grabbed the man's body and tossing it over my shoulder joint before turning around and letting my magic thrum in for a moment before I reached out and _tugged_. A moment later, a pulse of familiar magic pulled back and my magic latched onto it. The next second I was standing in Papyrus and I's territory. Our territory consisted of two Massive forests, overall reaching thousands upon thousands of miles of land.

Long rivers thrumming with magic ran through the forest while poisonous plants were nestled at the base of nearly all the tall trees. The only demonic animal that was inhabiting our territory were the _Apostles_ , vicious man-eating birds that Papyrus had bred and tamed using his magic. They were viciously obedient towards Papyrus and would immediately flock towards him whenever any potential threats were located. They required no food or sleep, and only needed water to survive making them the perfect security.

Speaking of Papyrus..I looked forward, walking through the trees and seeing our den. Our den was a huge cave made up of tough silver rock with protective Runes carved into the outside and inside walls. The archway of the cave was covered by a cloth like permanent magic that hanged in front of the entrance, completely blocking all view from the outside and keeping the temperature inside the den the same. Apostles that were perched in the tree's surrounding the den instantly went on guard before relaxing upon seeing me, releasing a soft slow melody to alert Papyrus that I was home. I heard footsteps move rapidly and I walked closer to the den's entrance before the cloth like magic was pushed aside and Papyrus's faintly excited face greeted mine.

Papyrus had what my race would call a cute face, with soft bone structure and wide eye sockets that were usually sleepily blinking. Skeletal sheep horns curled around his head and faintly one could see light green magic glowing at the sharp end.

Papyrus was dressed in a thick coat of soft black wolf fur that hung around his Esophagus securely. He also had a light colored tunic resting on his clavicle with a darker pair of pants.

Papyrus wrapped his skeletal arms around my waist, purring as he smelled the scent of blood coming from the man splayed over my shoulder. " _Food?"_ Papyrus said simply, nuzzling my blood stained tunic with his eye sockets closed. I chuckled, _"Yeah bro, food."_ I patted his skull gently before I started to head towards the entrance of our den, Papyrus trailing me. 

The main area of our den was an open room with a wide archway on the wall opposite of the entrance to our den. On one wall was a sturdy black shelf displaying various enchanted severed heads from both Monsters and Humans with splatters of dried blood beneath them and their permanently frozen expressions being the only sign that they were dead. Enchanted crimson weaving's displayed a shine as if they were dipped in fresh blood. Papyrus had made the weaving's himself, and if he needed a little help with getting ingredients..Never let it be said that I wouldn't do anything for my bro.

A hide of fur lay on the floor as soft padding and I walked towards the butchering area of our den. The butchering room was simple, with a section of wide carved out stone and smooth pieces of slabs that served as the place to cut up different prey that I had caught in the middle of the room. I made my way towards the slab, easily hefting the human over my shoulder and onto the slab. 

I grabbed the knife at my hip bone and cut off the clothes on the human before flexing my sharp claws that were at the point of my phalanges. " _Hey bro,"_ I called out " _Think this human is good enough for the shelf?"_ Papyrus walked over to my side, peering over the slab and carefully examining the human's face with a look of concentration. " _Trash."_

I chuckled before slitting the throat of the corpse, lifting his head up to where the oozed out of the neck. _"Your Verdict bro."_ I hummed, making a quick work of gouging out the eyes and handing them to Papyrus. " _Give these to the_ _Apostles for me."_ Papyrus obediently nodded, already moving towards the entrance of our den while I moved onto the human's chest area. **_*GORE WARNING*_** I sunk my claws deep into the corpse's chest and ripped out chunks of flesh. Deep red flesh came into view when I took chunks of the human's flesh and Hunger gnawed at my stomach. I paused for a moment before continuing my task of separating the edible parts of the prey from the non-edible. 

_Focus on your task Sans, it was all for Papyrus._ I thought to myself as I ripped deeper into the fleshy chest of the human, pulling out the parts of flesh I knew we could eat. I ripped deeper into the oozing chest, taking out various organs and intestines with no hesitation.

I had stopped being squeamish with Cannibalism long before the Humans had arrived.

I remembered the never ending pain of hunger that used to be _so so much_ worse than it was now. I remembered the ruthless hunt's I had to do if I wanted Papyrus and I to survive. I remembered the thick dust that clung to my body and the feeling of my sins crawling up my back due to it. So when the humans came, it was _easy_ to switch to a different more meat involved..diet. 

Shaking myself out of my thoughts, I continued to quickly work on my task.

Once I had finally separated all of the edible organs and meat from the body, all I needed to do was enchant them so they wouldn't rot and remain just as they had been before I took them out. Well, mostly. 

_"What should we have today bro?"_ I said and Papyrus blinked rapidly before responding _"heart please."_

I smiled at my bro and grabbed the bloody organ and ripped it in half, giving the bigger portion to Papyrus before devouring my half. My teeth sliced threw the delicious organ easily, a glowing tongue forming in my mouth instinctively as I savored the food before my magic would automatically transform the into magic energy. Human's tasted _divine._ The organ's especially so, they were delicious and packed full of rich flavor. Every human was different, some being more salty taste wise while others were almost fruity. 

I ran my tongue over my fanged teeth, the aftertaste leaving trace's that tasted of blood spice, and surprisingly enough, _Vaméérr_. Vaméér were a demonic species that most closely resembled one of the now long gone "pigs" that the human's had brought over. They were pitch black colored and had a long snout and multiple rows of teeth.

They were small in comparison to our Species, and despite its features, only ate plants. Of course, the plant's inhabiting our Realm were poisonous to almost all species who lived here, minus a couple specific few. Overall, they were the perfect prey. Vaméér tasted like herbal meat due to the poisons they consumed, though the species themselves were not poisonous, and were strong in flavour when you ate them. 

I looked towards my little brother and watched him happily eat his half of the heart, blood faintly staining his smaller fanged teeth while he finished it off. Still, i could tell that something was bothering him and I frowned. When Papyrus was done I asked him about it. " _What's wrong little bro?~"_ I asked, my voice having a faint growl to it as I scowled _"Some demon stupid enough to mess with you?" _

Papyrus looked at me in surprise for a few seconds, before rapidly shaking his head. " _It's not that, it's just.."_ I tilted my head curiously, wondering what was bothering him. A faint glow of green spread across his cheek bones _"I want to go the Valley with you today."_ Papyrus sheepishly admitted, and I blinked as Papyrus blushed even harder, this time looking guilty. " _I know you do alot for me, and that you protect me, so as a thank you I wanted to spend time with you somewhere beautiful. The Valley is the only place that would come close to that so.."_ Papyrus trailed off before he yelped as he was suddenly in the air. I picked Papyrus up from under his femur's so he had his arms resting on my esophagus. 

_"All you had to do was ask bro."_ and a split second later we were standing in the Valley of the First Hunt. Towering hills made up the peaks of the Valley and a shallow river ran through it. Papyrus's eye's widened and he beamed at me. _"Thank you Sans!"_

Papyrus grabbed my hand, grinning as he walked with me through the valley. Papyrus suddenly gasped and pointed to something in front of us. " _Sans! Look at that!!"_ Papyrus looked awed, leaning in curiously. A few feet in front of them, was a glowing white portal. Flashes of memories of when the portal from the human world, and a feeling of unease came over me. It was odd..Seeing something that looked so..pure in a Realm of dark Magic and hatred.

 _"wait, Papyrus don't-"_ Papyrus was already running over to the portal portal curiously leaning over it. My eye's faintly glowed and I walked forward towards him _"Papyrus I really don't trust this-"_ Something shoved me forward and I slammed into Papyrus just as a bright flash of white light made the portal suck us in.

Papyrus screamed and I shouted, lunging for Papyrus and whirling around so if we fell I would hit the landing first. I snarled, eye's in pin-pricks and glowing black with Rage. Red eyes gleaming with hatred and satisfaction were the last thing I saw before the world went dark.


	2. Chapter 2

**Notes for the Chapter:**

> For Reference - The Average Papyrus's are about 6'2-6'3, with the San's being 5'4-5'6. The Way the Demonic Race Height Wise works is the Average Adult is 6'8 to 7'1. By Demon Sizes, a couple inches shorter than 6'6 - 6'5 would be slightly shorter than average with Demons shorter than 6'3-6'2 being considered short. 
> 
> The Average Height for Demon/Monster Children, which are extremely rare as most Monster's don't have kids, are around the height of 5'1 - 5'4. 
> 
> So in Oc!Sans eye's, most of the Papyrus's are going to be considered slightly short while the San's are going to be TINY in his perspective.
> 
> FUN FACT: Oc!Sans is tall even for his Race, and is about 8'6 in height.

I groaned, my head throbbing as I tightly held Papyrus to my chest. I held a hand up to my aching skull, black spots dancing in my closed vision as I tried to remember what had happened. 

Papyrus and I had finished eating, and he wanted to go to the Valley. Memories of teleporting into the Valley of the first Hunt came to my mind, and I tried to figure out what I was forgetting. Papyrus saw something glowing, we went over there together and there was a white portal and then _ **...**_

My eyes flew open, magic flaring out as a pair of red eye's peered down at me. Flashes of the glowing red eyes that I had seen before I fell and the one's peering down at me molded into one, and I blindly ripped out the person's soul and turned it _BLUE,_ before slamming them backwards into whatever wall was there. 

Dim shouts barley broke through my hearing at all and I watched as Multiple Skeleton's filed in through a door. I snarled, clutching Papyrus tightly to my sternum as I pressed myself against the wall I was leaning on. Something was wrong with my hearing then, judging by the lack of sound I should have been hearing.

I quickly sent a flash of healing magic up to my head, something I had learned to do when I didn't have enough time to properly heal myself, and slammed down a shield of black protective Magic. Loud gibberish flooded my hearing and the Various different Skeleton Monsters came further into view, all of them wearing strange clothes that didn't look suited for fighting. There was about four of them, all having panicked expressions as they stood in front of the now confirmed Skeleton that I slammed into a wall.

I snarled, silently daring any of them to try and come close to me. My LV pulsed, my rising bloodlust and rage making my control slowly start to slip more than it already was.

I grinded my teeth together, forcing myself to ignore the violent urges that demanded to **_hurt_** and instead I tried to focus on the Skeleton's that were in the room with me. The two Skeleton's standing directly in front of the Red eyed Skeleton both looked at me, tense as I analyzed them.

The first was of Average height, if a little short, and was dressed in a lighter toned orange shirt, a color that wasn't often seen in the Demon Realm. He smelled faintly of some sort of odd fruit smell and..was that Nicotine I was smelling? It was definitely not strong smelling than normal Nicotine, and actually smelled rather sweet. I could guess that it was some type of Monster Made version of it then, but I could find that smell anywhere.

I grinned sharply, remembering how that one little product designed to aid humans in relaxing, made it all~ the easier to hunt them when they were running away.There was a reason after-all why most Demon's stayed away from strong scents, and it wasn't because of personal preference.

I moved my attention to the skeleton and paused, cocking my head to the side. The Skeleton next to the Nicotine Scented one was tiny, and If I hadn't seen how his movements reflected years of experience fighting, I would have pegged him as a child. He was also dressed in a odd baggy shirt, and again, it was a shade of bright blue that wasn't often seen the Demon Realm.

He had Unlike the Skeleton by his side, he had no noticeable scent and the only thing I and smelled from him was fresh air.

Both Skeletons were watching me carefully, however and I kept my eyes on them from my peripheral as I looked past them to see the other Skeletons that had come in with them.

The first Skeleton I saw was the one I had slammed against the wall. He was dressed in a tight black shirt with some sort of gibberish scrawled on the front, two small faint scars ran across his right eye. He was wearing some sort of ripped pants of some kind, and He was standing confidently, if a bit unsteady. He stared at me in a look of anger and..understanding? He seemed to be of average height though a little on the shorter side, and his fighting abilities were nothing to overlook judging by his fighting stance he had adapted when I looked at him. 

I kept note of his position against the wall and moved my attention to the tiny Skeleton next to him.

He, like the Skeleton in the Dark Blue, couldn't have been taller then 5'6 and was dressed in a similar baggy shirt that the other two Skeletons were wearing. He smelled like burning fire and chestnuts if they weren't poisonous. He had some sort of fur lining the hood of his shirt, he also had a familial collar on. He was definitely related to the scarred eye Skeleton then. Familial collars were Sacred in some Demon Cultures, and represented family bonds and fierce loyalty as well as Protection. He had the same bright red eye's that the Skeleton next to him had was glaring daggers at me, his pupils glowing with red magic. I flexed my claws, black magic intertwined as I growled at him. I wouldn't hesitate to use them to whatever monster got in my way of protecting Papyrus, Familial bonds or not. 

He glared, eyes flashing but I ignored him and scanned the Skeleton who was currently right beside him. He was just as short as the other two, and had a odd white shirt on. _(I would be able to find him easily if I were to hunt him.)_ He had a lighter blue sash that was tied around his esophagus, and smelled like a "candy" that I had found so long ago when the human's first came.... ** _lt that made me hungry_.** I stiffened, feeling my LV stirring and I looked away from him.

The final Skeleton in the room had almost exact same build as the Nicotine scented Skeleton and the Scarred Eye Skeleton. He was dressed in a bright orange shirt with the same script on it that the Scarred Eye Skeleton had on his shirt, though it seemed to be in a more bold font. He had a long bright red scarf loosely around his esophagus, much like the sweet scented Skeleton, and he frowned unhappily at me. It was jarring..how he seemed to remind me vaguely of my brother.

I shifted Papyrus closer to my side, growling lowly and sent a thrum of magic to strengthen my shield even more. _It didn't matter if the strange Skeleton reminded me of my brother, if any of them ever even looked at my brother aggressively.. _

**_T H E Y W O U L D B E D U S T B E F O R E T H E Y H I T T H E G R O U N D_ **

___________________________________________________________________________________________________________________________________________

**Notes for the Chapter:**

> In the Demon Realm, Time flows at hyper-speed compared to the Human World. 200 years in the Demon Realm is only 6 years in the Human Realm. 
> 
> Papyrus is 200 years old, which in human years means he's 6 years old. Sans on the other hand, is 800 years old which makes him 24.
> 
> I hope you enjoyed the Chapter, and I wish you all a happy day/night wherever you are!~


	3. Chapter 3

**Summary for the Chapter:**

> Room Arrangements~

**ROOM ARRANGEMENTS**

**SECOND FLOOR BEDROOMS**

******LEFT SIDE RIGHT SIDE**

**(UnderTale). (HorrorTale)**

**Classic Axe**

**CreamPuff Sugar**

**(UnderSwap) (Dusttale & Killer Sans)**

**Blueberry Dust**

**Stretch Murder**

**(UnderFell) (MobTale)**

**Red Roulette**

**Fell** **Sniper  
**  
 **MIDDLE ROOM  
** **(???)  
** **Oc!Sans & Oc!Papyrus**


	4. Chapter 4

**Summary for the Chapter:**

> Sans thinks about the Surface, and how each AU pair came into his Timeline. 
> 
> He just hopes that whatever the noise was that came from the Basement isn’t going to be a problem.

**Notes for the Chapter:**

> Woo~ This is a long chapter, so enjoy! I wanted to go more into depth then just explaining when the AU Skeleton's got to the Mansion, (The place where they are all living), and really go into details with some of their backgrounds and make it realistic.
> 
> Also Trigger Warning, There’s some implied attempted Rape!

When Sans came to the Surface, full of dread and waiting for the next **RESET** , he was shocked when they all walked down the Mountain.

He didn't even fully register the fact that things _were_ changing until Toriel hosted a meeting with the purpose of finding everyone homes on the surface to live in.

He and Papyrus contemplated it, and in the end moved into a big three story Mansion that had a large basement and a garden that opened into the thick forest that surrounded their new property.

(For More Detail)

The first Floor was the living room and dining room area. The kitchen a couple feet away from the two separate rooms.   
  
Beneath that was the basement, which was where the Machine was located.

The Second floor was where all of the Bedrooms were located, and there were about 13 bedrooms in the massive hallway. 6 rooms on each side of the Hallway with one room being on the back wall in between the two Sides.

( _~~I know, a lot of rooms but their going to need them in the future~)~~_

The third floor was the Entertainment area, with multiple different rooms like a Gaming Room, A Training Room & A Music Room.

There was also a large greenhouse on the property, its location being a couple meters away from the Mansion.

Sans had even taken extra precautions and "hired" Undyne to lace Offensive & Defensive protective magic onto the Gate & fence that surrounded their house.

Papyrus soon found a new hobby in gardening with the help of Toriel, and life seemed to slowly get better and better.

He was finally able live peacefully on the Surface..

At first, he felt numb and couldn't believe it.

He knew that the **PLAYER** had long since abandoned their morals, and was only doing a Pacifist run for entertainment. It was why for the first couple weeks after they arrived on the Surface, Sans felt nothing but constant anxiety and dread.

When was the **PLAYER** going to **RESET**?

How long would they all be up here before they were back Underground? And then, the vessel that the player controlled, Frisk, vanished.

Toriel and Papyrus along with most of the Underground searched and searched, but no matter what they did, they couldn't find Frisk.

Sans was..conflicted on how to feel.

He knew that the child, if you could even call it that anymore, wasn't at fault for what the **PLAYER** did. But for countless Reset's, Sans only lived in constant fear of "what would happen this timeline?", "Would the PLAYER finally get bored and go back to constant genocide runs?" and to suddenly not have the vessel that Sans associated the PLAYER with suddenly vanish..

He couldn't find in it himself to not be relieved.

And when it set in that he might be able to live without fear of the **RESETS** , It inspired something in him that he hadn't felt for a long time.

He _wanted_ to learn more about science, he _wanted_ to experience that enjoyment that came with it, he _wanted_ watch his brother enjoy himself and have fun above ground, and most of all, he _wanted_ to be **_free_**.

In the end, it was what drove him to fix the Machine. And at first, that was all it was going to be, and then he remember how much he _loved_ Science, and the project that he started as a way to resume an old hobby turned into something more.

It was shocking the first time when two Skeletons looking vaguely like him and his brother came through the Machine when he was fixing it. 

They were just as confused as he was, and they introduced themselves as "The Magnificent Sans!" and "Papyrus." 

It was disorienting to see, but fascinating how they seemed to have "switched personalities" with him and Papyrus.

A quick CHECK on both of them confirmed what Sans had suspected and it was of discovered that they were from an AU (The _acronym for Alternate Universe)_ called Underswap.

It was easy to work out the meaning behind the name, and just as Sans thought, their sudden visitors explained where they came from and Sans found that everyone was swapped in either their Personality or Job. They were definitely from an AU then.

Not to say that that was all their new Guests were, both Blueberry & Stretch, as they were later called, had their own aspirations and flaws that were entirely their own.

_(They took the first two bedrooms farthest away from the staircase on the Second floor, right next to Sans & Papyrus’s room.)_

In fact, they were so unique that they couldn't even be called the same people as them, both for Physical build and Personality. _(Further Testing would have to be done to see if they were genetically related to him & Papyrus later)_

Papyrus, who was temporarily confused at their arrival, soon excitedly took on the nickname "Creampuff" and eagerly got to know their new Guests. Sans himself took on the name "Classic" as to not confuse anyone.

A few weeks later, four new Guests arrived through the Portal.

The first pair immediately looked to fight when they came from the portal, and it took both him and Stretch's magic along with Blueberry and Papyrus to calm them down enough for the first pair to stop trying to attack them all.

The two were from an AU called Underfell, a place full of distrust and fighting, the evidence of sprawled across their bones in the form of multiple scars.

It took a lot of convincing and explaining before UF!Papyrus let any of them close to him and UF!Sans, and eventually after a lengthy conversation about where they were and how they came here, they were somewhat pacified.

They choose the names Red and Fell, Red for UF!Sans and Fell for UF!Papyrus, and choose two rooms right next to Blue & Stretch.

The second pair that had come through alongside Red and Fell were more tense and silent, with heavy accents and dressed in sharp suits, silver weapons glowing with magic in hand. They were from an AU called Mobtale, an AU full of crime and Politics. And while the two weren't as outright aggressive as Red and Fell, they clearly had no qualms about hurting Papyrus and him if it came down to it.

The two had listened to the explanation that he had given to Red and Fell before choosing the names Roulette and Sniper, Roulette for MT!Sans and Sniper for MT!Papyrus, before quickly choosing two rooms right across from Red and Fell on the second floor.

_(8 of the 14 Rooms on the Second Floor were now taken)_

Soon enough, the previously empty house quickly filled up, the number of Resident's only continuing to grow as the Machine brought more AU's to the Mansion. 

The next pair was from Underlust, an AU with a tragic backstory hidden by the cover of sex. They were both dressed in tight, revealing clothes that were ripped up.

It was..uncomfortable, how they both reacted when they woke up from where they had been passed out by the Portal. It was pure panic mixed with overwhelming fear and a resigned determination to die trying rather than lay down and take it painted across their faces that had Sans having flashbacks to the Judgement Hall.

Sans immediately stepped back, mind racing as he then sat down, and explained where they were and how they got to his timeline. 

A long uncomfortable silence filled the room, before UL!Sans gave a sigh of relief and promptly passed out, UL!Papyrus collapsing not a second later.

Sans immediately shouted for Papyrus, and when he turned around and saw all 6 Skeletons by the basement doorway alongside his Papyrus, he said nothing and instead began informing them of the situation.

Blue rushed forward, gently looking over the two's passed out figures looking for ways to heal them based on their injuries while Roulette and Sniper scanned the two for signs of fighting. When both Roulette and Sniper's faces dropped into looks of grim anger, Sans suspicion about pieced what had most likely been attempted to the two roughed up Skeletons from an AU named "Underlust" was confirmed.

Fell and Red wore matching looks of Rage, while Stretch grabbed a monster cigarette from his pocket and lit it using his magic, hands clenched in restrained anger.

Papy worriedly sat next to the two passed out Skeletons and went besides Blue, trying to make sure the two Skeletons were comfortable. 

After Blue healed them to the best of his ability, which was saying a lot given his affinity with Healing Magic, Papyrus then picked up UL!Sans while Sniper picked up UL!Papyrus before both headed up to the infirmary which was located on the first floor near the Dining room.

It took a solid day of round the clock monitoring and some strong healing on Blue's part before the two were conscious again, and even then the two had a constant fever that seemed to be magically induced. 

In a haze of dazed drowsiness, UL!Sans explained the story of his AU, how the fertility rate dropped dangerously low after they were all sealed underground, how the first fallen human, Chara, possessed the soul of LUST and how their father, Gaster, was the Royal Scientist in charge of extracting this element and injecting it into the Monsters in the Underground.

It backfired, and instead of boosting fertility, it made the Monsters crave sex and loose their morals and become sick and be in excruciating pain if they didn't have sex for long periods of time. 

UL!Papyrus then chimed in, talking about how some Monsters resorted to Rape when they couldn't find a suitable partner, instead choosing to force themselves onto the few unwilling who the drug didn't work for. UL!Papyrus then explained that he and his brother had built up an immunity to the drug, instead battling against the painful urges and making sure they were strong enough to defend themselves, and that the fever was a temporary side-effect of it.

The two didn't talk more past that, and nobody tried to force them to.

Eventually, when they two healed and starting interacting with everyone, they both soon became more comfortable and choose the names Hearts, for UL!Sans, and Nurture, for UL!Papyrus. They picked the rooms that were next to the Mobtale brothers. _(Their were now 6 Skeletons on the left side , and four Skeletons on the right. There were four more rooms on each side left.)_

Hearts quickly became close friends with Roulette and Sniper, being relaxed near the two and sharing the same sense of humor, though Hearts had more sex jokes than any other type of joke he could pull off. Nurture got along well with Fell and Red, his energetic but passionate attitude making the two less aggressive.

Weeks later, another two pairs came through the portal, this time however..Only one person came from each AU.

The first, was from a AU that was nameless.

The Sans was the main focal point of the AU, and his stats showed he already had the title of Killer!Sans.

Sans scanned his code briefly while he was **CHECKING** him. He had slaughtered most of the Underground when he was controlled by his Chara, and it had taken a severe effect on him, turning him into a mere shell of his original self. His LV was _19_ _._

The Skeleton that arrived at the same time as him had a remarkably similar story, only he had gone insane from Genocide runs and had grown to have a lust for LV, his Papyrus's ghost followed him and he was the only one able to see him.

His AU was called Dusttale.

After having to have a long tough battle in which every monster in the house had to participate in to defeat the two, it was universally decided that Therapy was going to have to happen after they managed to knock the two out.

And they did just that, after finding the best people available for them, the entire household decided to take up therapy as well, just in case. _(Honestly, Sans knew they should have gone earlier)_

It took weeks of attending therapy and slowly gaining the two's trust and showing them the outside world before they both became stable enough to actually have a conversation with them.

The two stayed close together even after they both became familiar with the other people in the house, and they took up the names Murder, for KL!Sans, and Dust, for DT!Sans. (They took the last two rooms on Blue and Stretch’s Side of the Hallway)

And then, the machine had spit out a darker AU than any of them had seen. ( ~~ _Just wait until you see my Sans & Papyrus)_~~

  
The skeleton came out of the portal holding a blood stained Meat Cleaver, his clothes just as bloodied as his weapon as he eerily grinned at them.

If Sans thought that Fell and Red had bad injuries, they didn’t measure to _this_ guy at all.

A large section of the New Skeletons skull on the right side completely fractured, leaving a gaping hole behind. His left eye socket opposite of his fractured side was pitch black, and he probably, no definitely, couldn’t see out of that side.  
  
His Papyrus had jagged teeth that looked painful to talk with, and towered over fell, who was one of the tallest Papyrus’s in the home. 

Safe to say, everybody in the room was understandably intimidated by the new Skeletons. In the end, after a rather horrifying Conversation, they talked about their AU, HorrorTale.

Sans grimaced as the Sans talked about it, describing the starvation and cannibalism that happened after their war. Papyrus shivered, and Sans comfortingly rubbed his brothers arm.

Papyrus then frowned, clearly upset for the New Skeletons despite being extremely intimidated by them, and told the two to follow him to the kitchen.

The New Skeletons attention snapped Papyrus, and Sans quickly went to his brothers side while they walked up from the basement to the first floor.

When they reached the Kitchen, Papyrus eagerly went through the cabinets till he found the biggest steak they had about to turn on the stove..and promptly had the steak ripped from his hands as HT!Sans tore open the package and ripped it apart for him and his brother. 

Papyrus’s face dropped in shock, exclaiming loudly that the two shouldn’t eat it raw before he flinched back from HT!Sans glare over the raw steak in his mouth.

Sans constant smile twitched, and he glared at HT!Sans.

Once the two were done, Blue nervously suggested a change of clothes for the two, and for the New Sans to put down his weapon.

The other Sans responded by putting down his meat Clever, and pulling out an Axe that he had in his inventory.

After Blue spoke, Sans stepped up and offered to show them where they could choose their rooms, he took Roulette with him during the tour.

_(They picked two rooms on the right, leaving one more room left on the right side.)_

Eventually HT!Sans choose the name Axe, due to it being his favorite weapon, and HT!Papyrus choose Sugar, surprisingly.

Days passed, and it became clear that Sugar’s teeth made it so talking was both Painful and troubling.

Blue and Papyrus were determined to help Sugar, so they teemed up and convinced Axe into letting Sugar see a Dentist, with his supervision, they then went on a hunt to find a Dentist that operates on Monsters.

Soon enough, they found one and after signing a contract that any harm or damage they would pay for, Sugar got an appointment.

Turns out, Sugars teeth, while damaged, could be fixed and for a week straight, Sugar, Axe & Blue went to the Dentist and slowly saw how Sugars teeth started to “heal”

When all of the procedures were done, and days of healing happened, Sugar could eat & speak without any pain. It was adorable how excited Sugar was, and Blue & Papyrus got a big hug, while Axe murmured a quiet “thank you” to the two.

It was awkward, at first, having everyone in one house together. But slowly, a pattern was formed. There was breakfast at 8:30-9:50, and there was specific people who cooked on specific days.

Sniper, who was an excellent cook, made the meals on Monday and Tuesday.

Fell worked with Papyrus, as the two balanced each other out in terms of cooking/baking. Fell made the meals, but was hopeless with desert, and Papyrus made Dessert and baked, he couldn’t cook to save his life. 

Blue/Blueberry cooked on Thursday, and it was random who cooked on Friday.

Everybody did their own chores, and if they wanted to, they could get a job. Nobody _had_ to pitch in, he and Papyrus had enough money to last them centuries, but if a person wanted to pay some rent, they could.

Then, on a freezing cold day in the middle of winter, when almost everyone was hanging out in the living room, a loud noise of something banging against sounded from the basement.   
  


Everyone tensed, and Sans scanned the room to check if anybody was missing.

”Well now,” Sans said, and everyone in the living room looked to him. “Red and Fell aren’t here.”   
  
At once, everyone in the living room started talking, and Sans waited for a moment before he calmly leaned back on the chair he was sitting on and looked towards Papyrus who was sitting beside him on the couch.

Papyrus looked at him in question, and Sans lazily waved his hand. 

Papyrus blinked his eye sockets for a moment, before realization flooded his face and he eagerly stood up and clapped loudly.

The sound bought back everyone’s attention, and Sans spoke again. “Alright, Now let’s go check it out. Keep your magic ready, and try not to attack immediately.”

Sans looked around for confirmation. Blue nodded rapidly, stretch simply _stretching_ for a moment before standing up and nodding. Red and Fell scowled, but nodded as-well, Sniper and Roulette nodding, hands already resting on their guns. Hearts and Nurture glanced at each other before Hearts gave Sans a quick thumbs up and a wink. “You got it Chief~“

Dust and Murder exchanged glances and shrugged, while Axe grinned at Sans, Sugar curiously nodding.

”Let’s do this” Sans said, and stood up and walked to the Basement stairs.

**Notes for the Chapter:**

> This chapter was fun to write, mainly because I actually looked into all of the AU’s Backstory's. 
> 
> I’m still debating on the AU Names, but if anyone wants to give me some suggestions I’ll definitely consider it!
> 
> I tried to keep the House description Vague, since I’m going to go into more detail about it in the future!~ Also, if your confused on the Room Arrangement, Just look at Chapter Three.
> 
> The List of AU’s in the house currently are:  
> Underswap  
> Underfell  
> MobTale  
> UnderLust  
> Killer Sans (No AU Name)  
> Dusttale  
> HorrorTale


	5. Chapter 5

**Summary for the Chapter:**

> Back in Present Time, Oc!Sans "meets" the rest of the Skeletons, and promptly attacks them.
> 
> Backup is called and Horror and Oc!Sans kinda communicate-..What did he say?

**Notes for the Chapter:**

> Sorry for the wait! I have been stacked with homework and two of my relatives caught COVID. I have literally been so tired that I straight pass out on the weekends and basically sleep for most of the day on my days off. 
> 
> (Teenage angst am I right-)
> 
> I am heavily sleep deprived right now, and I have consumed 8 cups of coffee, so forgive me if you find any misspellings that I couldn't find when I was proofreading. (I am somehow both exhausted and energized at the same time) 
> 
> Also, when I say "snarled" and "growled" I mean literally. Oc!Sans isn't pulling some childish imitation bullshit, he's actually using his non-existing vocal cords to somehow produce sounds an animal would make. (Think like how feral animals do)
> 
> I will try to update earlier but no guarantees.
> 
> (This) = Inner Thoughts
> 
> "This" plus bold = Talking
> 
> TRIGGER WARNING!! Violence, Cussing,

I felt my soul pound against my sternum, the familiar rush of magic only aiding my rising rage as the various Skeleton Monsters surrounding me began to speak in that _damn_ incomprehensible language again.

I concentrated on making sure I had enough magic if they decided to go on offense, feeling Papyrus’s horns dig into my clothed rib cage as his small form pressed tightly onto my tensed one as I kept my eye sockets locked on the Skeletons in front of me.

None of them looked particularly threatening, and it was odd that they all didn't have any sort of enchanted items or weapons.

No Demon would willingly meet an unknown monster without some sort of weapon, so the Skeletons in front of me were either dumb enough to not understand basic survival, or they were ridiculously confident in their strength.

On top of that, none of the Skeleton Demons had horns, just smooth bone-and while it was true that a couple rare few didn't have their full horns due to injury, most if not _all_ Demons at least still had some sign of where their horns originally were. 

Their Magic was another thing that was different, It was so..tame, compared to the magic I had felt in the past, especially from a Skeleton Demon. (M **em** or **i** **es o** f _t ** ~~hat~~**_ ** ~~ _man's_~~** **m** _ag **i** c, s_ **o** _ **s** **u** f **f** **oca** ti **n** gl **y d** ark_ **i** _t_ _ **m** a **d**_ _e_ **me c** ho **ke** wh **en** I **wa** s **y** _ **o** un **g** e **r, I re** me **mb** er **t** h **e** t **h** ic **k** d **us** t ~~t~~ hat **ha**_ d ~~_**c** lu_ ** _ng_** t~~ ** ~~o~~** _ ** ~~his body~~...)**_

The feeling of something slamming into my barrier knocked me out of my thoughts, instinctively strengthening the barrier around Papyrus and I as I watched the tiny scarred eye skeleton slam his magic roughly onto the barrier.

He loudly started saying something to the other unknown skeletons as he moved from his position from over his brother and faced towards me, starring determinedly at me even as he flinched when I opened my mouth in a display of aggression.

I snarled as the sweet smelling skeleton scrambled towards the scarred eye skeleton, shouting unintelligible words frantically as he tried to stop the scarred eye skeleton from continuing his assault on my barrier.

I could feel eye light's disappear, my LV _burning_ against my soul and I threw away any hesitation I had away when I saw the scarred eye Demon smirk in a cocky, arrogant way.

I wasn’t going to just lay against this wall with Papyrus in my arms _hiding_ behind a shield, while some _arrogant low leveled_ demon attacked me.

I moved forward a step before I slightly turned and set Papyrus behind me, making sure that he was in safe distance from any potential backlash before I faced the Skeleton Demons fully.

I reached for my magic, feeling the familiar heat rush through my bones before I directed it into my palms, cocking my head to the side as I grinned with anticipation as I lifted my hands up.

6 glowing eyelight's met mine, and I chuckled as I abruptly summoned my attack.

Four rows of jagged bones surrounding one giant G. Blaster formed on both of my sides instantly, they were both pitch black in color, with two deep gouges in it's skeletal shape serving as eyes.

Four sharp horns sat on the its head, a completely unhinged jaw floating a few inches away from the main "body" of the Gaster Blasters, painting the already terrifying weapon an even more eerie picture when suddenly the Skeleton in dark blue made a high pitched ringing noise from his mouth.

I stiffened as rapid footsteps reached my hearing, and I scanned the room, keeping the Skeletons in my peripheral as my eyes caught on the door that the Skeletons had come through a second before it burst open, revealing 7 more Skeletons.

The Skeletons I saw were of the same similar heights as the other pairs of Skeletons that were originally in the room with me, the first being tiny, and the Second being of Average height. _(Though they were all of varying heights, the consistent size difference seemed to be the main pattern)_

The first two Skeletons of the 7 were dressed just as oddly as the first 6 Skeletons, with the shorter one having a black sleeveless shirt that had slits in the sides that showed his ribs, loose shorts and a thick fur coat with a vibrant colored cyan fur resting on his shoulders.( _No weapons to be seen)_

The taller of the two had on a loose dark jacket ( _it didn't look useful for protection),_ with a lighter colored pink shirt that covered his esophagus. He had white gloves on and was wearing black pants. ( _No weapons or enchanted objects to be seen on him either_ )

The pair of Skeletons behind them had grim expressions on their faces, both of them moving forward with a silent precision that had my intuition whispering ways I could attack them the instant they were within range as they continued their path to me.

The first one had on a dark roughed up fur coat with a dark shirt underneath it, a sharp knife clutched in his hand with his right eye being wholly red and the left having a ring of red with a purple and blue eyelight, that wasn't what stood out about him though _, rather it was the bright red target shaped soul that glowed against his shirt._

I paused, staring at the Skeleton as I observed the bright red soul against his chest. How the fuck was that possible? _._ ** _._**

Every monster had fucked up their soul due to trauma at some point in their lives, if they even survived that long, but their souls still resembled a soul, and not...whatever that thing was. ( _Focus Sans, analyze the others)_

The other skeleton had a thin some sort of smooth black substance sliding down from his eye sockets and had a knife clutched in his hand that was covered by some inconvenient looking glove that left his phalanges uncovered. ~~(Its a fingerless glove Oc!Sans)~~

The third pair that came in looked like more familiar, at least in terms of how their injuries looked like. The first was taller than the rest of the other taller Skeletons so far, save for the red skeleton I had slammed into a wall, with sharp teeth that had some sort of wire wrapped around it and small round pitch black eyes. _(He seemed to have thinner , more angular bones then the rest of the other Skeletons)_ He was dressed in big dark blue shirt and had on some soft looking pants. _(Again, not good for protection)_ He also had a faded red scarf that was piled in front of his esophagus that looked roughed up. 

The shorter Skeleton next to him had a chunk of his skull missing on the right side, his eye on the opposite side of his skull being pitch black. _(probably blind on that side judging by the way he was facing towards me)_ He was dressed in a dark red jacket that had some sort of stain at the bottom _(it smelled faintly like animal blood)_ , a meat cleaver clutched in his hand.

I grinded my teeth together, feeling the sharp points roughly rub together before I grinned.

Fighting 6 Demon Skeletons would have been entertaining if a little challenging, but fighting _13_ unknown Demons at once... _ **It was going to be thrilling, and if my brother hadn’t been passed out behind me, this would have been even more enjoyable~**_

I urged my Gaster Blasters forward, watching as the giant maw of both of the weapons opened, revealing a huge gathering of pitch black attack magic rapidly forming in the center, and with a simple mental command for it to attack, the G. Blasters at my sides fired.

The powerful surge of deadly magic shot forward, the jagged bones at my side slicing through the air towards the Skeletons at the same time.

The Skeletons went into action immediately, teleporting away from the blast and dodging the bones expertly as I continued my attack and sent hundreds of bones in a steady but ruthless onslaught.

I brought my hands up in a quick fluid movement, feeling how my LV pulsed as I tapped into a mere fraction of my magic supply and summoned more Gaster Blasters to my side, not stopping my storm of attack for a second. ~~( I ignored how dizzy I felt using my magic so quickly after I just passed out,~~ ** _I had to protect my brother._ )**

Suddenly the sound of Papyrus's low groans caught my attention and my gaze snapped from the Skeletons to Papyrus, watching as he brought his hands to his skull and groaned.

Concern rushed threw me as I saw how my brothers normally apathetic expression was currently scrunched up in pain as he brushed his hand bones against his horns. I swore as i whirled around when the sound of a loud whistle echoed through the air, snarling as I remembered I was in battle as it seemed that my careless distraction was all it took for them to start firing their own attacks and I was suddenly slammed into the ground.

I groaned, feeling pain race tear through my body as my body met the stone cold ground harshly. I was already moving a second later, eye-sockets glowing as I growled and prepared to attack, ignoring the cryptic shouts from the Skeletons when the Skeleton with a hole in his skull stepped forward and with a rough voice, spoke. 

" **You..Need..Not..Dominate..We..Submit.."**

..What?

**Notes for the Chapter:**

> Oc!Sans & Oc!Papyrus don’t speak english, they have their own language that they are fluent in that was the main language in their AU/Realm. This language has some major similarities to Horror's original language, allowing Horror to kinda communicate with Oc!Sans, with some mistakes of course. 
> 
> Also, I saw a headcanon about Sugar getting braces, and it fits with my Au, so Sugar now has braces XD
> 
> I hope you enjoyed the Chapter! ❤️


End file.
